Phenotypic plasticity- a key to environmental responses

Maanantai 23.9.2019 klo 16.54 - Mikko Nikinmaa

We have argued that individual variability is very important in responses to toxicants, not just unwanted noise (Nikinmaa and Anttila 2019. Individual variation in aquatic toxicology: Not only unwanted noise. Aquatic Toxicology 207, 29-33; the article is open access, so everyone is free to read it). Reading all the work nowadays with the outset that plasticity is integral to environmental responses convinces me more and more that plasticity of the responses of animals and individual variability are very much overlooked features in how animals can tolerate environmental changes. Just recently, scientists from Israel (Segev et al 2019. Phenotypic plasticity and local adaptations to dissolved oxygen in larvae fire salamander (Salamandra infraimmaculata). Oecologia 190, 737-746) exposed salamander larvae from stream and pond environment to normoxia and hypoxia. The hypothesis was naturally that, since stream larvae never get exposed to hypoxia whereas pond larvae do, pond larvae would respond more to hypoxic conditions than stream larvae. A simple measure of responding, a change in gill size was taken. However, the results show that regardless of the origin of the larvae, the gill size change between normoxia and hypoxia was the same. This is possible only if the animals can respond plastically to oxygen level. If plasticity is great, and is maintained, genetic changes are not required for environmental responses. In fact, genetic changes are a worse alternative than large plasticity within a genotype, since variation achieved by genetic heterogeneity will decrease as soon as conditions are such that some genotypes of the population will not tolerate them. That will not happen, if the variance is a property of one plastic genotype.